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  • 1
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 102 (1995), S. 2727-2736 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Optical absorption spectra of Li4H and Li9H clusters have been recorded by depletion spectroscopy in the visible range. From comparison with ab initio calculations, geometries of both clusters are identified. The hydrogen atom assumes a peripheral position bridging two and three Li atoms in the planar and three-dimensional structures of Li4H and Li9H, respectively. Na4F and Na9F clusters are also theoretically studied and it is shown how the strong electronegativity of the F atom leads to different geometries than in lithium hydrids. Finally, the metallic character of these clusters is discussed and in both cases, the hydrogen or fluorine atom localizes one valence electron. However, the optical absorption spectra are much broader than in pure Lin and Nan clusters due to the lower symmetry. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 104 (1996), S. 1427-1440 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We show that a comparison of the depletion spectra of Na+n (n=2–9,11,21) clusters recorded at low temperature and optically allowed transitions determined for the stable structures using ab initio methods accounting for electron correlation allows the assignment of the cluster geometry to the measured features. Due to the large mobility of atoms in alkali metal clusters, the influence of temperature on structural and electronic properties is significant. The lowering of temperature reveals new spectroscopic features which are structure dependent. Optical response properties of small cationic Na+n clusters are characterized by rich molecularlike spectroscopic patterns, also with increasing size, and differ substantially from those found for neutral clusters. It has been clearly demonstrated that not only the number of valence electrons but its mutual interplay with the geometric properties determine optical response features. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Pediatric surgery international 12 (1997), S. 145-147 
    ISSN: 1437-9813
    Keywords: Key words Malignant renal tumors ; Wilms’ tumor ; Ureteronephrectomy ; Favorable histology ; Unfavorable histology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The authors report the treatment results of 89 children with renal tumors (excluding carcinoma) seen from 1988 to 1992, 71 (79.8%) with favorable-histology Wilms’ tumor (survival 86%) and 18 (20.2%) with unfavorable histology, including anaplastic nephroblastoma, clear-cell sarcoma, and rhabdoid tumor (survival 61%). Preoperative chemotherapy (ChT) was given to 46 patients (survival 84%); none was given to 43 with either tumors in the 1st year of life, massive hematuria, or tumor growth during ChT (survival 78%). There were 3 tumor ruptures in the latter group compared to 1 in the former group.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Pediatric surgery international 12 (1997), S. 145-147 
    ISSN: 1437-9813
    Keywords: Malignant renal tumors ; Wilms' tumor ; Ureteronephrectomy ; Favorable histology ; Unfavorable histology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The authors report the treatment results of 89 children with renal tumors (excluding carcinoma) seen from 1988 to 1992, 71 (79.8%) with favorable-histology Wilms' tumor (survival 86%) and 18 (20.2%) with unfavorable histology, including anaplastic nephroblastoma, clear-cell sarcoma, and rhabdoid tumor (survival 61%). Preoperative chemotherapy (ChT) was given to 46 patients (survival 84%); none was given to 43 with either tumors in the 1st year of life, massive hematuria, or tumor growth during ChT (survival 78%). There were 3 tumor ruptures in the latter group compared to 1 in the former group.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1572-9486
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The aim of this contribution is to show that quantum chemistry has suitable tools to extract the specific properties of small metallic and mixed non-stoichiometric clusters which cannot be obtained by extrapolation from the bulk properties to the atom. For this purpose, first the main features of the methods used for the calculations of the ground and excited states of clusters valid at zero temperature (T = 0) will be sketched and the factors determining accuracy of results will be pointed out. The structural and optical response properties of cationic clusters as a function of size will be presented and compared with experimental data. The series of non-stoichiometric alkali-halide clusters containing single and multiple excess electrons will serve as prototypes to study a possible “metal-insulator transition” and “segregation into metallic and ionic parts” in finite systems. Second, an outline of ab initio molecular dynamics methods based on gradient corrected density functional approach with gaussian basis used for determination of temperature dependent ground state properties will be presented. Different temperature behavior of distinct type of structures will be illustrated on an example of cluster.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 9 (1999), S. 183-187 
    ISSN: 1434-6079
    Keywords: PACS: 31.15.Ar Ab initio calculations – 31.15.Dv Coupled cluster theory – 31.50.+w Excited states – 36.40.Mr Spectroscopy and geometrical structure of clusters
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. We present calculations of absorption patterns in large energy intervals for the stable structures of oxygen-doped- and pure-silver clusters using the linear-response-type approach which allows one to correlate all 11 and 6 electrons per Ag and O atoms, respectively. For this purpose, we designed a new 11-electron relativistic effective core potential (11e–RECP) for Ag atoms at the correlated level of theory, which, together with the associated AO basis set, provide an accurate description of excited states. This has been evidenced by the comparison of our results with available experimental data. We found that inclusion of d electrons in the RECP, as well as in the correlation treatment, is important for an accurate prediction of the complete absorption spectra. Moreover, the influence of d electrons of Ag atoms becomes pronounced, even for structural properties of AgnO clusters. Also, the electrons of oxygen are strongly involved in excitations besides those of Ag-valence electrons, leading to intense transitions spread in a large energy interval. The role O plays in Ag n O clusters differs substantially from the one it plays in oxygen-doped alkali clusters, because of the participation of the d electrons of Ag atoms.
    Type of Medium: Electronic Resource
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